Abstract: LCC-HVDC DC transmission technology has significant advantages in long-distance and large capacity transmission. At present, the power grid becomes a system with deep coupling of AC and DC. Because of the need to consume a lot of reactive power, the DC system brings serious challenge to the voltage safety control of the system. Due to the large capacity of LCC-HVDC and the flexibility of converter control, a model predictive control (MPC) method for LCC-HVDC system to participate in long-term voltage stability control is presented in this paper.Firstly, the self recovery model of load is considered, and the quasi steady state model of voltage stability in AC and DC system is established. Based on this model, the sensitivity of the LCC-HVDC control variable to the system voltage locus is determined by using the trajectory sensitivity technique.Based on the voltage trajectory sensitivity, the LCC-HVDC system model predictive control method is proposed to improve the voltage stability of the system. The transmission power of the LCC-HVDC system is adjusted by on-line rolling, the voltage trajectory changes in response to the system, and the voltage stability is improved.The simulation results show that LCC-HVDC has great potential to participate in voltage stability control, and the proposed LCC-HVDC model predictive control method can effectively enhance the long-term voltage stability of the system.